<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    #box{
      width: 200px;
      height: 200px;
      background: red;
    }
  </style>
</head>
<body>
  <div id="box"></div>
  <script>
    function enablelongTap(ele) {
      let event = new CustomEvent("长按")
      let timer = null
      ele.addEventListener("mousedown", () => {
        clearTimeout(timer)
        timer = setTimeout(() => {
            // 触发事件
            ele.dispatchEvent(event)
        },500)
        let move = () => {
          clearTimeout(timer)
        }
        let end = () => {
          clearTimeout(timer)
          document.removeEventListener("mousemove", move)
          document.removeEventListener("mouseup", end)
        }
        document.addEventListener("mousemove", move)
        document.addEventListener("mouseup", end)
      })
    }
    // 长按
    let box = document.querySelector("#box")
    enablelongTap(box)
    box.addEventListener("长按", e => {
      console.log("这是一个长按事件")
    })
    
  </script>
</body>
</html>